The present invention relates to bicycle front derailleurs and more particularly to a front derailleur including a housing having a support extension extending in a support direction along the bicycle frame beyond a hinge of a tubular clamp.
The load-bearing element of a bicycle front derailleur is a housing part that is connected to a tubular clamp which fastens the housing part to a bicycle frame. The housing part is also connected to a chain guide movable to shift the chain between various chainrings. The shifting motion is initiated in a parallelogram mechanism by a rotating part connected to a pull cable.
EP 1 314 636 A2 discloses a front derailleur that includes a fixed member having a pivotable clamp, a chain guide and a parallelogram having two parallelogram arms. The parallelogram movably couples the chain guide to the fixed member. For this purpose, two pivot points are located on the fixed member, allowing a pivoting movement of both arms of the parallelogram member. The shifting motion is initiated by pulling a pull cable connected to one of the parallelogram arms in the direction of the larger chainring. The shifting force in the other direction is provided by a return spring. The shifting forces for shifting the chain from a small chainring to a neighboring larger chainring are considerably greater than in the other direction. To shift the chain to a larger chainring, the return spring must also be wound up. The torque introduced on the derailleur by the pull cable is supported by the relatively thin fixed member and the clamp on the bicycle frame. This requires a correspondingly high-grade material for the fixed member and the clamp and a firm clamping on the frame, which may damage the frame surface.